1. Field of the Invention
The present invention relates generally to ink-jet photographic quality printing and, more specifically, the printing of a graphical image from edge-to-edge of a specific size of paper.
2. Description of Related Art
The art of ink-jet technology is relatively well developed. Commercial products such as computer printers, graphics plotters, and facsimile machines employ ink-jet technology for producing hard copy. The basics of this technology are disclosed, for example, in various articles in the Hewlett-Packard Journal: Vol. 36, No. 5 (May 1985), Vol. 39, No. 4 (August 1988), Vol. 39, No. 5 (October 1988), Vol. 43, No. 4 (August 1992), Vol. 43, No. 6 (December 1992) and Vol. 45, No.1 (February 1994) editions.
In the state of the art, photographic quality printing using ink-jet printers has been developed, e.g., some of the HP.sup.tm DeskJet.sup.tm and OfficeJet.sup.tm models offer such capability. FIG. 1 illustrates a typical DeskJet hard copy apparatus, in this exemplary embodiment a computer peripheral printer, 101. A housing 103 encloses the electrical and mechanical operating mechanisms of the printer 101. Operation is administrated by an electronic controller (usually a microprocessor-controlled printed circuit board) 102 connected by appropriate cabling to a computer (not shown). Cut-sheet print media 105, loaded by the end-user onto an input tray 120, is fed by a suitable paper-path transport mechanism (not shown) to an internal printing station, or "print zone," 107 where graphical images are created or alphanumeric text is rendered. A carriage 109, mounted on a slider 111, scans the print medium transported through the print zone 107. An encoder subsystem 113, 201 is provided for keeping track of the position of the carriage 109 at any given time. A set of ink-jet pens, or print cartridges, 115x ("K" for black, "C" for cyan, "M" for magenta, "Y" for yellow, "F" for fixer solutions) are releasably mounted in the carriage 109 for easy access. In pen-type hard copy apparatus, separate, replaceable or refillable, ink reservoirs 117x are located within the housing 103 and appropriately coupled to the pen set via ink conduits 119. Once a printed page is completed, the print medium is ejected onto an output tray 121. The carriage scanning axis is referred to as the x-axis, the print media transport axis is referred to as the y-axis, and the ink-jet printhead (not seen in this angle of the pens 115x) firing direction is referred to as the z-axis.
[To simplify explanation of the present invention, all print media compatible with ink-jet printing is referred to hereinafter as "paper. All ink-jet hard copy apparatus are referred to hereinafter as "printer(s)." All colorants are referred to as "ink." No limitations on the scope of the invention are intended by the inventor nor should any be implied.]
It is known in the art to make digitize photographic images, either by using a digital camera to take the photograph or by scanning a photographic print. It is common for end-users to desire photographic prints to be borderless, i.e., printed from top-to-bottom and side-to-side. In ink-jet printing, this type of printing is referred to as "full bleed." While the scanning axis of the carriage 109 generally extends beyond the width of the paper 105, printing perfectly edge-to-edge (whether leading-trailing edge or side-to-side edge is being considered) is impractical and ill-advised since ink drop overshoot will lead to ink being deposited into the printer mechanism.
Even if printing edge-to-edge is implemented without overshoot, any skew of the paper position would be revealed as a white edge or region. Generally, the likelihood of positioning a sheet without any skew is low. To print in full bleed requires the ability to detect the size of the paper, the ability to actively correct any skew of the paper, or the ability to actively compensate for skew of the paper. Thus, for borderless prints, the state of the art requires printing with a post-printing manual trimming.
There is a need for an ink-jet printing system allowing full bleed printing.